Preface

Electrostatics and dielectrics have important applications in modern society. The research on electrostatics and dielectrics has been very active, and the emergence and development of modern science and technology has made a great contribution to the in-depth study of various dielectric materials and electrostatics. This research has played a great role in promoting the further production and development of science and technology. However, with the continuous development of modern society, better characteristic requirements have been put forward for dielectric materials and electrostatics. More and more equipment needs to operate at high frequency, high voltage, high temperature, and other harsh conditions. Therefore dielectric materials need high performance requirements as well as good work stability. This book contains the research progress and application status of electrostatics and dielectrics in different fields.

There are eight chapters in the book. The first chapter is the introductory chapter of modern applications of electrostatics and dielectrics. The second chapter is about the electrostatic potential modulation of atoms. The third chapter examines the development of a new electrostatic eliminator using a pulse width modulation (PWM) inverter. The fourth chapter discusses the electrostatic effect application of touch screens. The fifth chapter analyzes the variable frequency motor insulation failure mechanism and improvement measures. The sixth chapter is about the dielectric analyzing model of soil moisture content. The seventh chapter discusses dielectric materials in the study of the calculation method of the rectangular waveguide. Finally, the last chapter is about the study of synergistic effect of mixed-gas dielectrics.

> **Dengming Xiao** Shanghai Jiao Tong University, China

**Krishnaswamy Sankaran** Radical Innovations Group - RIG, Finland

**1**

**Chapter 1**

and Dielectrics

*Krishnaswamy Sankaran*

phenomena of electrostatics.

common applications [1–5].

teristic behaviours of dielectric materials.

layers to truncate computational domains [12].

**1. Introduction**

Introductory Chapter: Modern

Electrostatics is one of the most basic, yet very important, branches of physics with applications in almost every domain. We observe how a plastic comb after its use on dry hair attracts small bits of paper. We are stunned by the power of lightning from dark rainy clouds during thunder storms. Time to time, we might have also experienced small electric shocks when we touch any metal after rubbing hands on certain materials. All these experiences have to do with the underlying

Materials are broadly classified into two large groups based on their electrical properties. Some are called conductors and the others are termed as insulators (or dielectrics). In dielectrics, contrary to metals, all charges are attached to specific atoms and molecules. Such charges are known as bound charges. These charges can be displaced within an atom or a molecule. Compared to the dramatic rearrangements of charges in a conductor under electric field, charge displacements in dielectric materials are only microscopic in nature. However, these microscopic displacements can have cumulative effects that are responsible for several charac-

Electrostatics-based applications are ubiquitous. Lightning conductors, surface coaters, electrostatic imagers, non-impact printers, industrial processes such as material separation, electrodialysis, static dischargers, etc., are some of the most

Dielectrics have been used for developing various devices particularly using their unique material properties. Recent advancements in material science have made it possible to develop and engineer devices for applications in elasto-optics, electro-optics, ultrasonic [6] and surface-mount electronics [7]. Dielectrics are also used to develop compact and efficient antennas [8]. There is an increase in the use of dielectrics for developing advanced defence applications [9]. Dielectric material properties can carefully engineered to develop artificial materials and coatings that can efficiently absorb or dampen incident electromagnetic waves. Such materials are both used in real-time stealth applications [10, 11] and modelling absorbing

Accurate modelling of dielectric properties is one of the most challenging tasks. For basic applications like studying oil spills on ocean surface, one can easily model oil spills as dielectric with complex permittivity [13]. Other advanced applications require more detailed modelling of dielectric properties. For example, dielectric elastomers are actively studied for applications involving artificial muscle actuators for robots and solid-state optical devices for various electronic components [14].

Applications of Electrostatics

#### **Chapter 1**
